Clam shell tag line assembly



May 29, 1962 J. H. CLARK CLAM SHELL TAG LINE ASSEMBLY Filed Feb. 2, 1959 64' j v 7'75. 4. 30 28 4 v 27 '2 66 2 -HJ g0 I l INVENTOR. 2 John H. C/ar/r ATTOR/Vf) United States Patent D 3,036,724 CLAM SHELL TAG LINE ASSEMBLY John H. Clark, 1020 S. Park, Independence, Mo. Filed Feb. 2, 1959, Ser. No. 790,609 4 Claims. (Cl. 214-657) This invention relates to power operated crane apparatus and more particularly, to a novel brake unit for controlling taking in and paying out of conventional tag lines employed for limiting swinging of a material handling clam shell or other device suspended from the boom of the crane.

Tag line assemblies to prevent turning of a crane bucket While in operation have been utilized for a long time to maintain tension on the crane bucket throughout the time the latter is raised and lowered or swung in a circle about the vertical axis of rotation of the crane boom. One widely used tag line assembly for the defined purpose comprises a cylinder rigidly secured to the boom intermediate the ends thereof and rotatably mounting a shaft having a coil spring surrounding the same and connected at opposed ends thereof to the rotatable shaft and the cylinder respectively. A pulley secured to one outer end of the shaft exteriorly of the cylinder and rotatable with the shaft, has a tag line secured thereto and wound around the same before passing to a point of connection to the clam shell or bucket suspended from the crane boom. Through the arrangement described, constant tension is placed on the bucket regardless of the direction of movement thereof to prevent turning of such clam shell about a vertical axis.

Although the tag line assembly conventionally used and as referred to above is satisfactory for preventing undesirable rotation of the clam shell, of necessity, the spring connected to the pulley shaft and the cylinder respectively is not of sufficient resiliency to interfere with exact raising and lowering of the bucket along a path of travel substantially perpendicular to the surface of the ground.

It is therefore the most important object of the present invention to provide a novel brake unit adapted to be utilized in conjunction with the tag line tension assembly set forth above to permit selective inactivation of the pulley having the tag line trained therearound and thereby prevent taking in or paying out of such tag line, whereby the clam shell or other device suspended from the boom may be moved into closer proximity to the crane chassis when desired by the simple expedient of stopping rotation of the tag line pulley and causing the bucket to swing about an arc defined by the length of the tag line as the clam shell is raised or lowered.

A further important object of the invention is to provide a brake unit for the purposes outlined above having novel means thereon adapted to engage the tag line pulley in stopping relationship thereto, whereby the operator of the crane may swing the bucket in toward the area beneath the intermediate portion of the crane boom by actuating the brake unit to stop rotation of the tag line pulley and thereby taking in and paying out of the line around the same. 1

Another important object of the invention is to provide a brake unit which may be utilized in conjunction with presently existing tag line tension assemblies, thereby obviating the necessity of discarding prior tag line assemblies in order to modify the crane so that the bucket suspended from the boom thereof may be swung inwardly toward the machine when desired.

A further important aim of the invention is to provide a brake unit which is constructed so that the universally available air or hydraulic pressure on the crane may be readily employed as the motive force for operating the ice brake unit and without substantial modification of the structure of the crane being required. 1

An equally important aim of the invention is to provide a simple, relatively inexpensive and efficient brake unit for a pulley and tag line tensioning assembly and which may be mounted on the boom of the crane in a manner so that the same may be readily removed or replaced as desired.

Other important objects and details of construction of the present brake unit will be described in greater detail hereinafter or will become obvious as the following specification progresses.

In the drawing:

FIGURE 1 is a fragmentary, perspective view of a crane boom having a clam shell suspended therefrom and particularly showing the normal disposition of a conventional pulley and tag line tensioning assembly for preventing rotation of the clam shell;

FIG. 2 is an enlarged, fragmentary, side elevational view of the pulley and tag line tensioning assembly shown 111 FIG. 1 and showing the relative position of the brake unit constituting the present invention, with a part of the tag line pulley being broken away to reveal details of the brake shoe and band therebehind;

FlG. 3 is an enlarged, fragmentary, bottom view of the instant br-a-ke unit and looking upwardly from within the central part of the crane boom;

FIG. 4 is an enlarged, fragmentary, end elevational view of the brake unit in its normal position relative to the pulley and tag line tensioning assembly.

FIG. 5 is a cross sectional view of the hydraulic motor for actuating the brake unit and illustrating the brake shoe biasing means therewithin; and

FIG. 6 is a fragmentary view of the pivotal interconnectron between the hydraulic motor and a crank for operating the brake shoe.

The pulley and tag line tensioning assembly broadly numerated 10 is especially adapted to be mounted on the boom 12 of a power operated crane 14 or the like. Control lines 16 extending from crane 14 and'passing over the upper sheave unit 18 on boom 12 suspend a clam shell or bucket 20 from boom 12 and also control opening and closing of clam shell 20.

lulley and tag line tensioning assembly 10 may comprise an elongatedcylinder 22 secured to boom' 12 in transversely extending relationship to the normally uppermost, parallel, horizontally spaced, outwardly facing angle lIOIlS 24 and 26. A number of U-bolts 27 and to be referred to in greater detail hereinafter, may be employed to releasably secure cylinder 22 to angle irons'24' and 26 of boom 12. The end of cylinder 22 proximal to angle iron 24, has a bearing therein rotatably carrying one end of a pulleyshaft 28 extending outwardly therefrom and rotatably mounting a relatively large tag linepulley 30 rotatable on an axisconcentric with the axis of cylinder Although not illustrated, it is to'be understood that shaft 28 extends the entire length of cylinder 22, with another bearing being provided therewithin maintaining shaft 28 and cylinder 22 in concentric relationship. An elongated coil spring 29 within cylinder 22 and surrounding shaft 28 is secured to the latter at a point adjacent pulley 30. The opposite end of the coil spring 29 is joined to cylinder 22 so that a constant tension is placed on pulley 30 regardless of the direction of rotation thereof. Bracket 32 depending from cylinder 22 has a pair of pulleys 34 rotatably mounted on the lowermost end thereof and between which the tag line 36 is adapted to pass before being connected to the clam shell, .as shown in FIG. 1.

A brake unit broadly numerated 38 and constituting the subject matter of the present invention, is adapted to 3 be mounted on boom 12 adjacent assembly 10. Unit 38 preferably includes a frame 40 provided with a rectangular metal plate 42, as well as angle irons 44, 46 and 4-8 welded to one face of plate 42 in parallel, spaced, transversely extending relationship, as best shown in FIGS. 3 and 4.

Plate 42 is secured to the underside of angle irons 24 and 26 in substantially parallel, longitudinal relationship with cylinder 22, one leg of U-bolts 27 passing through plate 42 at one longitudinal edge thereof, as illustrated in FIG. 3, while additional U-bolts 50 of substantially smaller size span respective angle irons'24 and 26 and pass through suitable openings in plate 42 at the margin thereof opposed to the edge receiving the defined legs of U-b-olts 27. Nuts 52-on the ends of U-bolts 27 and 50 extending through plate 42 releasably maintain the latter in tight engagement with angle irons 24 and 26, yet

.permit quick release of frame 40 from boom 12 when desired.

It is to be noted that plate 42 is secured to boom 12, with the angle irons 44, 46 and 48 located in proximal relationship to tag line pulley 30 and perpendicular to the axis of rotation thereof.

Crank 54 mounted on frame 40 includes a central stretch 56 rotatably carried by the upright legs of angle irons 44 and 46 and located in perpendicular relationship thereto for rotation on an axis parallel with the axis of rotation of pulley 30. A relatively short end stretch 58 integral with stretch 56 at the end thereof between the upright legs of angle irons 46 and 48, is disposed in median relationship to the latter and is parallel with the defined upright legs thereof. Stretch 60 of crank 54 integral with the extremity of central stretch 56 remote from end stretch 58, extends laterally from stretch 56 and is substantially longer than end stretch 58. It is to be -noted that stretch 60 projects laterally from central stretch 56 in a direction opposite to end stretch 58, although it is to be understood that all of the stretches of crank 54 lie in a common plane and including end stretch 62 integral with-the outer extremity of stretch 60 remote from central stretch 56. As best shown in FIG. 4, end stretch 62 projects outwardly from stretch 60 in parallelism with central stretch 56 and thereby perpendicular to opposed end stretch 58.

Semicircular brake shoe 64 has a cylindrical collar 66 secured to the outer convex face thereof in parallelism with the axis of a circle partially defined by shoe 64, with collar 66 in turn rotatably receiving end stretch 62 of crank 54. Means not illustrated in detail is provided for releasably securing collar 66 and thereby shoe 64 to .end stretch 62 of crank 54, yet permitting free rotation of brake shoe 64 relative to end stretch 62. A brake lining 68 is adhesively or otherwise secured to the inner concave surface of brake shoe 64.

As-indicated in FIG. 4, stretch 60 of crank 54 is of sufiicient length to cause collar 66 secured to brake shoe '64 to be disposed a distance substantially equal to that between shaft 28 and a plane through angle irons -24 and 26. Cylindrical band 70 welded to the normally innerrnost face of pulley 30 in concentric relationship thereto is of a width substantially equal to brake shoe 64 andis adapted to be engaged by lining 68 when shoe 64 is moved toward the axis of pulley 30 and shaft 28 upon rotation of crank 54 in a manner to be-specifiedin greater detail hereinafter.

Means for swinging crank 54 includes a cylinder 72 provided with a fluid-actuated,'reciprocablepiston 74 pivotally connected at the bifurcated outer end thereof to the extremity of end stretch 58'of crank 54 by means 'of a pin 73 passing through aligned openings in stretch- 58 and the bifurcations on the outer endot piston 74. Oppositely extending pins 75 secured to the outer surface of cylinder 72 in perpendicular relationship to the axis thereof, project through opposed upright legs of respective angle irons 46 and 48 and thereby permit cylinder 72 to rotate about the axis of aligned pins 75. Line 76 communicating with cylinder 72 at the end thereof away from piston 74, permits fluid to be directed into cylinder 72 in a direction to cause piston 74 to be moved outwardly therefrom. It is to be pointed out that a spring 77 is preferably provided within cylinder 72 for biasing piston 74 toward the innermost end of its path of travel.

It can now be ascertained that upon mounting of brake unit 38 on boom 12 adjacent assembly 10, the spring 77 within cylinder 72 biases piston 74 toward the inner end of its path of travel and thereby rotates crank 54 in a direction to maintain lining 68 of brake shoe 64 out of contacting relationship with brake band 70. During the time that piston and cylinder assembly 7274 is inactivated, tension is maintained on tag line 36 by virtue of the coil spring 29 disposed within cylinder 22. Thus, clam shell 20 is prevented from rotating during the time that the same is raised and lowered or boom 12 is swung about the vertical axis of rotation thereof.

However, if the operator of crane 14 desires to cause bucket 20 to be moved into engagement with the ground at a point in closer proximity to crane 14 than a straight line downwardly from the outer end of boom 12, he may readily accomplish this by causing fluid to be directed into cylinder 72 through line 76 whereby piston 74 is forced outwardly to rotate crank 54 in a direction to move brake lining 68 of brake shoe 64 into tight engagement with brake band 70. Since pulley 30 is prevented from rotating, tag line 36 cannot unwind from pulley 30 and therefore, clam shell 20 is swung about an arc defined by the effective length of tag line 36 as the bucket is raised or lowered.

It can be appreciated that the distance bucket 20 is swung toward crane 14 by stopping rotation of pulley 30 is determined by the relative height of clam shell 20 above the ground at the time that fluid is directed into cylinder 72 to swing brake lining 68 into stopping engagement with brake band on pulley 30.

Brake unit 38 is simple in construction, may be readily removed or replaced on boom 12, and does not contain parts which are complex and thereby liable to frequent breakdown. By virtue of the pivotal mounting of cylinder 72 on angle irons 46 and 48 and rigid connection of piston 74 to crank end stretch 58, the required swinging of stretches 60 and 62 about the axis of rotation of stretch 56 is effected without binding of the components which would preclude movement of brake lining 68 into firm stopping engagement with band 70. An important feature of the invention is the fact that brake unit 38 in no way interferes with the normal operation of pulley and tag line tensioning assembly 10, but may be operated by the craneman by the simple expedient of opening or closing a valve controlling flow of fluid into cylinder 72 through line 76.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

1. In a power crane having a swingable boom and a tag line tensioning assembly thereon including a pulley carrying a tag line and rotatably mounted on one end of a cylinder secured to said boom the combination with said pulley and boom of a brake unit for controlling the length of tag line reeled in by and payed out from said pulley, said brake unit including annular flange means secured to said pulley in lateral spaced relationship to the tag line receiving surface thereof for rotation therewith; an elongated brake shoe having an arcuate surface for complementally engaging the outer surface of said flange means; elongated crank means secured at one end thereof to said brake shoe intermediate the ends of the latter and swingably mounted on said boom adjacent said cylinder for shiftably mounting said brake shoe on said boom; and power actuated means operably coupled with said crank means at the opposite end of the latter and secured to said boom for swinging said crank means relative to said boom to shift said brake shoe into frictional engagement with said flange means, said power actuated means having yieldable means thereon for biasing said crank means in a direction to normally maintain said brake shoe out of frictional engagement with said flange means.

2. In a power crane as set forth in claim 1, wherein said power actuated means includes a fluid actuated device having a cylinder secured to said boom and a piston movable within said cylinder responsive to the application of fluid pressure within said cylinder, said piston having a rod extending outwardly from said cylinder and engaging said crank means, said yielda-ble means being positioned within said cylinder and engaging said piston for biasing the latter and thereby said crank means in said one direction.

3. In a power crane as set forth in claim 1, wherein said brake shoe is provided with a collar thereon intermediate the ends thereof, said crank means including a pair of parallel stretches and a transverse stretch interconnecting said parallel stretches, one of said parallel stretches being journaled in said collar and the other of said parallel stretches s-winga-bly mounted on said boom, said power actuated means being operably coupled with said other parallel stretch.

4. In combination, a power crane having an elongated, swingable boom and a clam shell mechanism adjustably suspended from the boom; a tag line assembly carried by said boom and including a cylinder secured to said boom intermediate the ends of the latter, a pulley rotatably mounted on said cylinder at one end thereof, a tag line operably coupled with said pulley and secured at the outermost end thereof to said clam shell mechanism, and a coil spring within said cylinder and operably coupled with said pulley for biasing the latter for rotation in a direction to normally reel in said tag line; and a brake unit for controlling the length of tag line reeled in by or payed out from said pulley, said brake unit including annular flange means secured to said pulley in lateral spaced relationship to the tag line receiving surface thereof for rotation therewith; an elongated brake shoe having an arcuate surf-ace for complementally engaging the outer surface of said flange means; elongated crank means secured at one end thereof to said brake shoe and swingably mounted intermediate the ends thereof on said boom adjacent said cylinder about the longitudinal axis of said crank means for shiftably mounting said brake shoe on said boom; and power actuated means operably coupled with said crank means at the opposite end of the latter and secured to said boom for swinging said crank means relative to said boom to thereby shift said brake shoe into frictional engagement with said flange means, said power actuated means having yieldable means thereon for biasing said crank means in a direction to normally maintain said brake shoe out of frictional engagement with said flange means.

References Cited in the tile of this patent UNITED STATES PATENTS 1,012,005 Pearson Dec. 19, 1911 1,210,846 Royce Jan. 2, 1917 1,437,734 Kessler Dec. 5, 1922 2,166,479 Ruddock July 18, 1939 2,250,171 Wilkins July 22, 1941 2,283,784 Billings May 19, 1942 2,412,412 Meili Dec. 10, 1946 2,435,740 Edwards Feb. 10, 1948 2,471,346 Peterson et al May 24, 1949 2,619,201 Crookston Nov. 25, 1952 FOREIGN PATENTS 736,944 France Sept. 26, 1932 

